RU2272325C1 - Installation for researching on liquid magnet - Google Patents

Abstract

FIELD: the invention refers to training aids and may be used in practical work in physics course.

SUBSTANCE: the installation has in series connected: two flat induction coils, source of constant current, ammeter and rheostat. On a stand there are two fixed axles of rotating induction coils, on which two rigid brackets are pivotally suspended with their first ends and to their second ends are rigidly connected the induction coils placed in a vessel with liquid magnet installed on the stand provided with a scale with divisions in degrees.

EFFECT: the installation allows to take off dependence of Ampere force arising at interacting of the coils with current in liquid magnet from the value of this current and determine value of magnetic penetrability of liquid magnet and expands the field of researching.

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Description

The invention relates to educational devices and can be used in laboratory practice in higher and secondary special educational institutions at the rate of physics to study and deepen knowledge of physical laws and phenomena.

Known Kolbe device for demonstrating the interaction of two coils with current, suspended on a flexible cord on a tripod. (D. D. Galanin et al. Physical experiment at school, volume 4. Uchpedgiz, 1954, p. 125, Fig. 238). It allows you to demonstrate only the interaction of two coils with current, without measuring the Ampere force and taking into account the influence of the magnetic permeability of the medium on the interaction force.

A training device for studying the electromagnetic field is also known (RU patent No. 2210815, 08.20.2003, Bull. No. 23. Author: V. Kovnatsky) containing two toroids with an iron core (solid magnet). This device allows you to measure the characteristics of the electromagnetic field, but it cannot measure the magnetic permeability of the toroid cores.

Closest to the proposed installation is the installation (Fig. 4) for demonstrating the interaction of two coils with current suspended on two thin wires (O.F. Kabardin. Physics. Reference materials. M: Education 1991, p.184, Fig. 190.) The installation contains two flat inductors and a direct current source. When the coils are connected to a direct current source, one coil deviates from the other. When an iron rod is introduced into one of the coils, the other coil is deflected by a larger angle. However, this setup does not allow measuring the Ampere force during the interaction of inductors, and also to determine the magnetic permeability of a liquid medium in which these coils can interact.

The aim of the invention is to expand the functionality of this installation. This goal is achieved by the fact that the following are introduced into it: stand; two axis of rotation of flat inductors mounted on a stand; two rigid suspensions, the first ends of which are hinged on the axis of rotation of the flat inductors, and the second ends are rigidly connected to these coils and are the first inputs of the flat inductors, and their second inputs are thin insulated conductors wound on both hard suspensions; an ammeter and a rheostat, which form a series-closed circuit with two series-connected flat inductors and a direct current source; a vessel with a liquid magnet mounted on a stand, in which there are two flat inductors in one plane perpendicular to the axes of the inductors themselves and the axes of rotation of these coils; graduated scale in degrees mounted on a stand.

In Fig.1 and Fig.2 presents drawings explaining the principle of operation of the proposed installation. Figure 3 shows a General view of this installation, figure 4 - its prototype.

The proposed installation includes: 1 - a flat inductor; 2 - hard suspension; 3 - axis of rotation of a flat inductor; 4 - stand; 5 - a vessel with a liquid magnet; 6 - ammeter; 7 - rheostat; 8 - a direct current source; 9 - scale with divisions in degrees.

When conducting research with an artificially created liquid magnet (for example, a solution of iron chloride in water), it is necessary to measure the magnetic permeability of the medium each time. It is also important to determine the Ampere force in the interaction of coils with current in such a medium. Existing devices for measuring magnetic permeability (Manual for laboratory studies in physics edited by L.L. Goldin. M.: Nauka. 1973. p. 293-334; F.V. Kushnir. Measurement in communication technology. M .: Communication. 1970. p. 480-495) do not allow this. Consider how this is achieved in the proposed installation.

эти витки разойдутся на угол α от исходного положения. В жидком магнетике на круговой виток с током I₁ (фиг.1) действуют четыре силы: сила Ампера

, сила натяжения нити

, сила тяжести

и выталкивающая сила Архимеда

, где V_B - объем кругового витка, ρ - плоскость жидкого магнетика, m_B - масса витка и g - ускорение свободного падения.Let two circular turns with a current of I ₁ and I ₂ and a radius of R ₀ (Fig. 1) are suspended on two rigid identical suspensions with a length of 1 on the axes O ₁ and O ₂ . The coils are in the initial position at a distance r ₀ in a liquid magnet with magnetic permeability μ and density ρ. Circular coils are located in one plane perpendicular to the axes of rotation of the coils O ₁ and O ₂ , as well as the axes of the coils O ₃ and O ₄ themselves. Ampere

these turns diverge at an angle α from the starting position. In a liquid magnet, four forces act on a circular coil with current I ₁ (Fig. 1): Ampere force

thread tension

, gravity

and buoyancy force of Archimedes

where V _B is the volume of the circular coil, ρ is the plane of the liquid magnet, m _B is the mass of the coil, and g is the gravitational acceleration.

The equilibrium condition for each turn has the form:

or in projections on the x axis:

on the y axis:

From the expressions (1) and (2) we find:

, с которой круговой виток с током I₂ действует на виток с током I₁. Сначала найдем силу, с которой магнитное поле с индукцией

, создаваемое током I₂, действует на элемент

, принадлежащий контуру l₁ с током I₁ (фиг 2):Define the power of ampere

with which a circular coil with current I ₂ acts on a coil with current I ₁ . First we find the force with which the magnetic field with induction

created by current I ₂ acts on the element

belonging to the circuit l ₁ with current I ₁ (Fig 2):

в соответствии с законом Био-Савара-ЛапласаMagnetic induction

in accordance with the law of Bio Savara Laplace

(фиг.2) первого витка, и следовательно, R означает расстояние между элементами

и

обоих векторов, а вектор

направлен от

к

.where observation point A is an element

(figure 2) of the first turn, and therefore, R means the distance between the elements

and

both vectors, and the vector

directed from

to

.

Combining (4) and (5) we find the force:

The force with which a circular coil with current I ₂ acts on a coil with current I ₁ .

With the same force, a circular coil with current I ₁ acts on a coil with current I ₂ .

The analytical calculation of the double integral in formula (6) is impossible, therefore, its value was found by the authors by the method of numerical integration:

where R ₀ is the radius of the turns, r is the distance between the centers of the circular turns, which we find from figure 1:

Equating expressions (3) and (7) and taking into account the equality of currents in circular turns I ₁ = I ₂ , as well as expression (8), we find a formula for determining the magnetic permeability of a liquid magnet.

To reduce the amount of current consumed by circular turns, replace them with flat inductors of mass m, each of which contains N turns. Then the current I ₁ in expression (9) is replaced by I ₁ = NI, where I is the current flowing through one coil of the coil. In this case, the buoyancy force of Archimedes is F _A = ρgV, where V is the volume of the inductor.

Based on the introduced notation, we obtain the final expression for determining the magnetic permeability of a liquid magnet:

The experimental setup for the study of liquid magnet is presented in figure 3. It contains two flat inductors 1. Both coils 1 are suspended on rigid suspensions 2. The first ends of rigid suspensions 2 are motionlessly connected to inductors 1, and their second ends are hinged pivotally on the axis of rotation of 3 inductors, which are mounted on a stand 4. Flat coils inductors 1 are connected in series with each other, located in a vessel with a liquid magnet 5 in one plane perpendicular to the axes of the inductors 1 themselves and the axes of rotation 3 of these coils. The first input of each inductor 1 is a rigid suspension 2, and the second input is a thin insulated conductor wound on a rigid suspension 2. Serially connected flat inductors 1 are also connected in series with an ammeter 6, a rheostat 7 and a direct current source 8.

A vessel with a liquid magnet 5 is mounted on a stand 4, on which a scale with divisions in degrees 9 is installed. The position indicator on the scale 9 is a rigid suspension 2.

By changing the current in the circuit using rheostat 7, the inductors diverge at different angles α, the values of which are measured on a scale with degrees in 9. The current value is measured using ammeter 6. The measured values of the angle α and current I are substituted into formula (10) to determine the magnetic permeability of a liquid magnet. The remaining quantities included in formula (10) are indicated on the laboratory setup.

The dependence of the Ampere force F during the interaction of the coils with the current on the magnitude of this current can be calculated by the formula (7).

The technical and economic efficiency of the proposed installation for studying liquid magnetics lies in the fact that it provides an improvement in the quality of assimilation of the basic laws and phenomena of physics by students.

The proposed installation is implemented at the Department of Physics and is used in the educational process in laboratory studies on electromagnetism.

Claims (1)

Installation for researching a liquid magnet, containing two flat inductors and a direct current source, characterized in that a stand is inserted into it, two axis of rotation of the inductors mounted on the stand, two rigid suspensions, the first ends of which are hinged on the axis of rotation of the inductors, and the second ends are rigidly connected to the flat inductors and are the first inputs of the flat inductors, and their second inputs are thin insulated conductors wound on both suspension, an ammeter and a rheostat, which form a sequential closed circuit with two serially connected flat inductors and a direct current source, a vessel with a liquid magnet mounted on a stand in which two flat inductors are placed in one plane perpendicular to the axes of the inductors themselves and the axes of rotation of these coils, a scale with degrees in degrees mounted on a stand.

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